A New Approach in Testing Analog-to-digital Converters

Abstract: This paper describes a new approach in testing static parameters of analog-to-digital converters (ADCs). The input of an ADC to be tested is connected to a generator of saw-tooth impulses. In comparison to ordinary approaches, the measured decision levels are not related to zero potential but to the decision levels of an additional ADC, which is of same type as tested ADC. Approximating principle-based test system, with a digital-to-analog converter (DAC) in the feedback, measures these differences, which are in the extreme case in the range of a few least significant bits (LSB) of tested (additional) ADC. It has been proposed a special algorithm, to which output codes of tested and additional ADC enter, to control this DAC, which output is added through a resistive divider to the input of additional ADC. By using this approach, there are no special requirements on the precision of input sawtooth impulse generator and precision of the obtained integral non-linearity (lNL), differential non-linearity (DNL) characteristics mainly depends on DAC used. It was also shown that using 8 bit DAC the precision is in the range of a few hundredths of LSB. By simulations with MATLAB, the theoretical considerations are verified.